Physiographic patterns show a narrow coastal
plain, occasionally widened by river deltas, and a series of mountain ranges
roughly parallel to the coastline and separated by undulating plains.
Climate presents mild winters and warm
summers, with a warming trend observed in the 1990s. Precipitation values
oscillate around 500-700 mm a year, although means and averages make little
sense in front of strong inter-annual and intra-annual variations.
Population trends parallel the recent
history of Mediterranean cities. That is, rural migration and concentration of
population in large cities until approximately the mid 1970s, and the reverse
processes in the 1980s and 1990s. Thus, from centralized compact urban forms and
functions, the Barcelona region is undergoing a more dispersed pattern with an
increasing presence of features of what we call the diffuse city (or
"American model"): low density housing, a communications network built
for private transportation, and proliferation of metropolitan subcentres.
Fluvial networks of the Barcelona metropolitan region
River
Basin area (km2)
Annual mean average flow (m3/s)
Minimum flow in a dry year (m3/s)
Maximum flow (m3/s)
Date of maximum flow
Llobregat - Matorell
4 561
20.7
1.69
3 080
21-9-1971
Besos - Montcada
1 032
3.88
1.8
2 345
25-9-1962
Ripoll - Montcada
242
1.19
0.40
1 234
25-5-1962
Tordera - Can
Serra
802
5.65
0
1 280
20-9-1971
Extreme Events
Floods and droughts are a common
characteristic of Mediterranean water cycles. In the Barcelona region, there
have been major floods in 1962 (with possibly 1 000 people dead), 1971, 1988 and
1994. Local flashflooding is becoming increasingly important, especially in the
rapidly growing coastal plains north and south of the city. Diffuse inondation
after storms with intensities of 200 mm/day or more is also becoming common.
Drought conditions have become also more
frequent in the 1990s. In 1990, for instance, the region barely escaped the
imposition of supply restrictions. The winter of 1999-2000 has been in many
localities the driest winter of the century although, in accordance with the
Mediterranean climate, the following spring has been one of the wettest of the
last decade
